For efficient operation of the fuel cell, humidification of the electrolyte in the fuel cell may be essential. As a humidification device, a humidification device may operate by exchanging moisture between an exhaust gas as a wet gas discharged from the fuel cell and a dry gas supplied from the outside air.
In particular, as the humidification device used in the fuel cell, a compact humidification device having a low electric power consumption and a small installation space may be required. Accordingly, among several types such as a ultrasonic humidification, a steam humidification, and an evaporation humidification, a humidification device using a hollow fiber membrane may be frequently used in the fuel cell. For example, as illustrated in accompanying FIG. 7, a membrane humidifier 100 and an air blower 202 are included in an air supply system that supplies oxygen or air to a fuel cell stack.
As such, the outside dry air is supplied into the hollow fiber membrane of the membrane humidifier 100 by a suction operation of an air blower 202, and the exhaust gas or wet air discharged from a fuel cell stack 200 passes through the membrane humidifier 100. The moisture contained in the exhaust gas at this time may penetrate into the hollow fiber membrane, and thus, the dry air may be humidified.
As shown in FIGS. 8 and 9, a configuration and an operation of the conventional membrane humidifier will be described in more detail below.
As illustrated in FIGS. 8 and 9, the conventional membrane humidifier 100 includes a housing 101, and the housing 101 is formed with a supply port 102 for introducing the dry air, and an outlet 103 for discharging the humidified dry air. In addition, a hollow fiber membrane 106 bundle in which a plurality of hollow fiber membranes 106 are densely packed may be provided inside the housing 101.
In addition, in the housing 101, an inlet 104 for inflow of the wet air discharged from the fuel cell stack is formed at a first side, and an outlet 105 for discharge of the wet air is formed at a second side which is opposite to the first side.
In the operation of the membrane humidifier using the hollow fiber membrane having the above configuration, when the exhaust gas discharged from the fuel cell stack after the reaction or the wet air is supplied toward the bundle of the hollow fiber membrane 106 from the inlet 104 of the housing 101, moisture in the wet air may be separated by capillary action of each hollow fiber membrane 106 and the separated moisture may be condensed while passing through the capillary of the hollow fiber membrane 106 and move into the hollow fiber membrane 106.
Subsequently, the wet air from which the moisture is separated may move along the outside of the hollow fiber membranes 106, and thus, the wet air may be discharged through the outlet 105 of the housing 101.
Meanwhile, in the hollow fiber membrane having the above configuration, the ambient air or the dry air is supplied through the supply port 102 of the housing 101 by driving of the air blower, and the dry air supplied through the supply port 102 moves through the interior of the hollow fiber membrane 106. Since moisture separated from the wet air may readily move to the interior of the hollow fiber membrane 106 at this time, the dry air may be humidified by the moisture, and the humidified dry air may be supplied to an air electrode of the fuel cell stack through the outlet 103.
However, since the hollow fiber membrane 106 bundle is formed such that a plurality of hollow fiber membranes 106 are densely disposed, the wet air may not be introduced into the hollow fiber membrane through the inlet 104. Moreover, since the diffusion speed of the wet air through the hollow fiber membrane is substantially reduced, the wet air may not penetrate into the interior of the hollow fiber membrane.
In particular, within the housing 101, the wet air passing through the outside of the hollow fiber membrane 106 bundle may not smoothly penetrate into a central part of the hollow fiber membrane 106 bundle indicated by a hidden lines in FIG. 9 inside the housing 101, and may flow mostly around the hollow fiber membrane on the edge side. As consequence, the humidification efficiency of the dry air may be reduced.
As such, in the related arts, a membrane humidifier for a fuel cell and application thereof have been developed to improve the humidification efficiency by installing a removable cartridge type internal division module inside the housing of the membrane humidifier and by allowing the wet air to uniformly penetrate to the central part of the hollow fiber membrane bundle through a wet air inlet aperture formed in each of the internal division modules.
However, since the density of the hollow fiber membranes arranged along a length direction of the housing of the membrane humidifier is uniformly arranged, changes in flow velocity and differential pressure of the wet air may not be induced, and humidification effect may not be sufficiently obtained.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.